Horses are commonly transported by air freight in a common crate which is dimensioned for loading in the airplane and hence has a base dimension of the order of 8 feet by 10 feet.
This dimension is fixed by the transportation system and hence the crate to be carried on this base must fit onto the base. The standard technique to form the crate is by manufacturing four panels connected at right angles typically from wood frame covered on the inside by sheathing of plywood. The four panels are then knocked down at the delivery location and returned in flat. Up to now this has been considered adequate and the amount of room available within the predetermined dimensions has been considered adequate to contain four horses.